#include <GL/glew.h>
#include <GL/glut.h>

#include <stdio.h>
#include <stdlib.h>

void init()
{
  glewInit();

  GLfloat mat_spec[] = { 1.0f, 1.0f, 1.0f, 1.0f };
  GLfloat mat_shin[] = { 50.0f };
  GLfloat light_amb[] = { 0, 0, 0, 1.0f };
  GLfloat light_pos[]  = { 1.0f, 1.0f, 1.0f, 1.0f }; // xyzw, w=0 -> direct; w!= -> position
  GLfloat white_light[] = { 0.0f, 1.0f, 1.0f, 1.0f };

  glClearColor(0, 0, 0, 0);
  glShadeModel(GL_SMOOTH);
  glMaterialfv(GL_FRONT, GL_SPECULAR, mat_spec);
  glMaterialfv(GL_FRONT, GL_SHININESS, mat_shin);
  glLightfv(GL_LIGHT0, GL_AMBIENT, light_amb);
  glLightfv(GL_LIGHT0, GL_POSITION, light_pos);
  glLightfv(GL_LIGHT0, GL_DIFFUSE, white_light);
  glLightfv(GL_LIGHT0, GL_SPECULAR, white_light);

  glEnable(GL_LIGHTING);
  glEnable(GL_LIGHT0);
  glEnable(GL_DEPTH_TEST);
}

void display()
{
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  glutSolidSphere(1.0, 36, 24);
  glFlush();
}

void reshape(int w, int h)
{
  glViewport(0, 0, (GLsizei)w, (GLsizei)h);
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();

  if(w<=h)
    glOrtho(-1.5, 1.5, -1.5*(GLfloat)h/(GLfloat)w, 1.5*(GLfloat)h/(GLfloat)w, -10.0, 10.0);
  else
    glOrtho(-1.5*(GLfloat)w/(GLfloat)h, 1.5*(GLfloat)w/(GLfloat)h, -1.5, 1.5, -10.0, 10.0);

  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
}

int main(int argc, char* argv[])
{
  glutInit(&argc, argv);
  glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB|GLUT_DEPTH);
  glutInitWindowSize(500, 500);
  glutInitWindowPosition(100, 100);
  glutCreateWindow(argv[0]);

  init();

  glutDisplayFunc(display);
  glutReshapeFunc(reshape);
  glutMainLoop();

  return 0;

}
